Space

Astronomers expect that galaxies grow by swallowing smaller galaxies. But the evidence is usually not easy to see -- just as the remains of the water thrown from a glass into a pond will quickly merge with the pond water, the stars in the infalling galaxy merge in with the very similar stars of the bigger galaxy leaving no trace. But now a team of astronomers led by PhD student Alessia Longobardi at the Max-Planck-Institut für extraterrestrische Physik , Garching, Germany has applied a clever observational trick to clearly show that the nearby giant elliptical galaxy Messier 87 merged with a smaller spiral galaxy in the last billion years.


We have already had a view from the Mediterranean of Jupiter, Venus and the Moon in Seeing Jupiter In Daylight.  Jupiter and Venus are getting closer together in the sky, and on the 1st of July, at around 8:00 UTC, actual conjunction will occur, when the two planets are at the same Ecliptic longitude (referring the annual path taken by the Sun against our stellar background.)  At that time, the planets will be below the Horizon for New World observers.

An immense cloud of hydrogen has been observed dispersing from the warm, Neptune-sized planet Gliese 436b orbiting nearby star Gliese 436. 

The enormous gaseous tail of the planet is about 50 times the size of the parent star.  A phenomenon this large has never before been seen around such a small exoplanet. 
Using ESA’s Rosetta spacecraft, scientists have identified more than a hundred patches of water ice a few meters in size on the surface of Comet 67P/Churyumov-Gerasimenko. Rosetta arrived at the comet in August 2014 at a distance of about 100 kilometers and eventually orbited the comet at 10 kilometers or less, allowing high-resolution images of the surface to be acquired. 

An international team of scientists has found some of the best evidence yet that Venus, Earth's nearest neighbor, is volcanically active.

In combing through data from the European Space Agency's Venus Express mission, the scientists found transient spikes in temperature at several spots on the planet's surface. The hotspots, which were found to flash and fade over the course of just a few days, appear to be generated by active flows of lava on the surface.

"We were able to show strong evidence that Venus is volcanically, and thus internally, active today," said James W. Head, a geologist at Brown University and co-author of a paper describing the new research. "This is a major finding that helps us understand the evolution of planets like our own."


Have you ever seen Venus in full daylight ? It's a fun experience. Of course we are accustomed to see even a small crescent Moon in daylight -it is large and although of the same colour of clouds, it cannot be missed in a clear sky. But Venus is a small dot, and although it can be quite bright after the sunset or before dawn, during the day it is just a unconspicuous, tiny white dot which you never see, unless you look exactly in its direction.

Now that Philae has woken up, we may be on the brink of major steps forward in our understanding of comets. We already know that perhaps as much as 30% of a comet consists of dust and organics. Now we'll be able to look at this close up. Why, though, do most scientists expect Philae to find pre-biotic chemistry? Is there any chance of life? Also, where else in the solar system can we look?

The ancient oceans of Jupiter's Europa and Saturn's tiny Enceladus are hidden beneath an ice sheet kilometers thick. They may have ET microbes, even multicellular swimming creatures around hydrothermal vents. Or they could have imperfectly reproducing "protocells"; a window into the first stages of evolution. 

These conditions, which make them so habitable, and interesting for astrobiology, may also make them especially vulnerable to invasive species. Cassini orbiter found geysers at the south pole of Enceladus, continually venting sea water from its ocean into space, as ice particles. This may give us a wonderful opportunity to look at ET life in our solar system without interference from Earth life.

If an extraterrestrial race - or indeed later civilization on the Earth looks at the relics of our space explorations - one thing they might notice is our fondness for placing flags and pennants in space. All the space faring nations have signed the Outer Space Treaty. So these are not claims of territory (forbidden by the treaty) but rather, celebrations of national pride and accomplishment.